A Study Of Evaluating The Health Of Windbreak And Sand-fixation Forest In Minqin

The windbreak and sand-fixation forest in the lower reaches of Shiyang river is the most important ecological barrier,which play an important role in maintaining the stability of the oasis,sustainable production and living in Minqin,improving ecological environment of Minqin desert,ensuring the ecological safety of Minqin region,curbing the badain jaran and tengger desert to lecture and so on,At present,due to the influence of factors such as climate change and human activities,especially the declining of underground water level,the reducing gradually of surface hydrologic,the consuming of soil moisture,the formation of sand surface crust,and the worse of ecological hydrology environmental,had caused degradation of the sand-fixation,thus,it is of great significance to construct evaluation index system of windbreak for managing and operating the windbreak and sand-fixation.In this paper,identify and selecting evaluation index system is by widely collecting and consulting relevant information,and then got the indicators data by analyzing ecology field sample plot survey and indoor experiment method,setting the weights of evaluation indexes based on the integrated application of relevant principle of analytic hierarchy process model,the HI model was used to build windbreak health index and built windbreak level zoning map by using GIS technology,and analysis the main influence factors of windbreak and sand-fixation forest from the multiple perspectives,putting forward some management suggestions.The results of the study were as follows:(1)There were mainly four vegetation communities by analyzing the data of field investigation,including H.ammodendron community,N.tangutorum community,T.chinensis community,and C.mongolicum community.and had 12 types(H.ammodendron,H.ammodendron+ N.tangutorum,H.ammodendron+ C.mongolicum,H.ammodendron+ R.songarica;N.tangutorum,N.tangutorum+ T.chinensis,N.tangutorum+ R.soongarica,N.tangutorum+ C.mongolicum;T.chinensis,T.chinensis+ R.soongarica;C.mongolicum,C.mongolicum+ A.desterorum Spreng).(2)We had established health evaluation index system based on community level,which contained four primary indicators and 23 secondary indexes,set the evaluation index weight of windbreak forest and calculated health index of windbreak forest for providing basic data of windbreak forest health evaluation.(3)The health index of windbreak and sand-fixation forest was 0.6790,indicating it was general in Minqin.The health index of sample plot(44.36%)was between 0.60 and 0.75,the 31.24% sample plot was health,the health index of sample plot(24.41%)was between 0 and 0.60,but there was no better health sample plot.(4)The health index of windbreak and sand-fixation forest showed that ordinal ranking of four vegetation communities: T.chinensis community > N.tangutorum community > H.ammodendron community > C.mongolicum community,ordinal ranking of 12 types:N.tangutorum+ T.chinensis > T.chinensis+ R.soongarica > N.tangutorum > N.tangutorum+ C.mongolicum > N.tangutorum+ R.soongarica > T.chinensis > H.ammodendron+ N.tangutorum>H.ammodendron+ R.soongarica>H.ammodendron>H.ammodendron+ C.mongolicum>C.mongolicum>C.mongolicum+A.desterorum Spreng.(5)There was a big difference about health index of windbreak and sand-fixation forest in Minqin.The lateral variations of health index was that barrage area was poor,quanshan area was general and lake area was health.The ordinal ranking of health index of windbreak and sandfixation forest was barrage area(0.5947)<quanshan area(0.7143)<lake area(0.7665);The vertical variations of health index was that oasis,desert transitional zone and desert were all general,but the ordinal ranking of health index of windbreak and sand-fixation forest was desert(0.7039)>oasis(0.6842)>desert transitional zone(0.6471).(6)We had made correlation analysis between health index of windbreak and sand-fixation forest and ten indexes by collecting the data about natural environment and social economic conditions.The result was that the health index of windbreak and sand-fixation and soil water content and soil organic was significantly positive correlation,and the underground water level was significantly negative correlation.(7)Selecting the windbreak and sand-fixation including H.ammodendron and N.tangutorum as the object in Minqin,the geostatistical analysis function in Arcgis was used.The results showed that the most of H.ammodendron and N.tangutorum were in degradation or sever degradation,respectively 79.62% and 81.54% of the total area in Minqin.